1. Field of Invention
The present invention relates to the field of marine seismic data acquisition systems and methods of using same. More specifically, the invention relates to systems and methods for acquiring towed streamer seismic surveys in less time, or using fewer seismic resources, or increasing the fold using the same seismic resources.
2. Related Art
The performance of a marine seismic acquisition survey typically involves one or more vessels towing at least one seismic streamer through a body of water believed to overlie one or more hydrocarbon-bearing formations. WesternGeco L.L.C., Houston, Tex., currently conducts high-resolution Q-Marine™ surveys, in some instances covering many square kilometers. In many areas of the world hydrocarbon reservoirs located in structurally complex areas may not be adequately illuminated even with advanced towed marine streamer acquisition methods. For example, the shallow, structurally complex St. Joseph reservoir off Malaysia produces oil and gas in an area that poses many surveying and imaging challenges. Strong currents, numerous obstructions and infrastructure, combined with difficult near-surface conditions, may hinder conventional survey attempts to image faults, reservoir sands, salt domes, and other geologic features. A survey vessel known as a Q-Technology™ vessel may conduct seismic surveys towing multiple, 1000-10,0000-meter cables with a separation of 25-50 meters, using the WesternGeco proprietary calibrated Q-Marine™ source. “Q” is the WesternGeco proprietary suite of advanced seismic technologies for enhanced reservoir location, description, and management. For additional information on Q-Marine™, a fully calibrated, point-receiver marine seismic acquisition and processing system, as well as Q-Land™ and Q-Seabed™, see http://www.westerngeco.com/q-technology.
To achieve high density surveys in regions having a combination of imaging and logistical challenges, a high trace density and closely spaced streamers may be used, however, this presents the potential of entangling and damaging streamer cables and associated equipment, unless streamer steering devices are closely monitored and controlled. While the Q suite of advanced technologies for marine seismic data acquisition and processing may provide detailed images desired for many reservoir management decisions, including the ability to acquire wide- and/or full azimuth data, the ability to acquire marine seismic data in less time and with less cost, or to increase the fold while also increasing the diversity of azimuth and offset, are constant goals of the marine seismic industry and would be viewed as advances in the art.